Ambient condition detectors have been found to be useful in providing an indication of the presence of the respective condition. Smoke detectors have been found useful in providing early warnings of the presence of airborne particulate matter such as smoke.
Known smoke detectors often include a housing with an internal smoke chamber. Either an ionization-type or a photoelectric-type smoke sensor can be located in the housing.
Vents are located in the housing. Ambient air circulates into and out of the housing in response to movement of the adjacent atmosphere.
Air circulation in a region being monitored does bring the airborne particulate matter into the housing. Depending on the nature of the air currents, this can be a faster or a slower process.
In large commercial buildings air circulation is often achieved by centralized heating and cooling systems. Building control systems alter air flow in response to preset schedules. Hence, there may be times of minimal or no circulation such as evenings or weekends. There continues to be a need for solutions to these minimal or no circulation situations.